The present invention relates to a method and apparatus for inspecting tubular members to detect corrosion and thinning and more particularly to a method and apparatus using ultrasonic energy to measure the thickness of the wall of the tubular member. The use of ultrasonic means for detecting anomalies or other types of imperfections in tubular members is well known. There have also been attempts to adopt ultrasonic means for measuring the thickness of the tubular members. While these attempts have been partially successful, they have not displayed the data in a way that allows the operator to detect the presence of corrosion or a thinning of the tubular member. The ability to detect thinning and corrosion of the tubular members is important especially in the case of heat exchangers where possible tube failure could cause serious problems.